Vertical metal studs are widely used in building construction, particularly in conjunction with commercial buildings, for the non-load-bearing interior walls. The studs generally are covered with drywall which is attached to them to form the interior walls of the structure in which they are used.
In the past, vertical metal studs in non-load-bearing interior walls of a building were connected directly between a track on the floor at their bottoms and a top track secured to the horizontal joists for floors or roofs of the building. Such construction has resulted in substantial problems, in that little if any vertical displacement of the floor or roof, at the top of the studs, could be tolerated.
The fixed relationship of the non-load-bearing studs and the floors or roofs connected to the top ends of the studs results in longitudinal compressive stresses on the studs, which frequently causes the studs to buckle laterally at intermediate locations, creating cracks or distortions in the walls of the building in which they are used. These longitudinal forces applied to the studs result from vertical displacement of the floor or roof of the building above the studs. The fixed relationship of the non-load-bearing studs, in the case of variations in load for office floors above the rooms in which the studs are used, or in the case of a heavy load of snow or the like on a roof, causes a significant downward pressure on the vertical non-bearing studs. If the studs are rigidly secured at both the top and bottom, between the floor of the room and its ceiling, unsightly and unacceptable cracks occur in the wall covering. In addition, the integral structure of the wall is weakened as a result of the buckling or partial buckling of the studs. When the load is lessened (in the case of an office building, by all of the workers leaving at the end of a day, or in the case of a roof, by the melting of snow), the cracks in the walls increase as the walls expand in response to the lessening vertical pressure on the studs. The studs themselves undergo a stretching or lengthening after their earlier buckling, which further contributes to the weakness of the wall.
Efforts to overcome the problems of a rigid interconnection between vertical studs in non-bearing walls and the ceilings or floors above them, by allowing relative movement of the ceiling or floor with respect to the studs, have been made. One effort is disclosed in the United States patent to Gilmour No. 5,040,345. This patent is directed to the addition of a stud clip to the head track for allowing vertical floating movement of a floor or roof structure above the stud to take place. The clip has a pair of opposing flanges, which are secured directly to the downwardly depending flanges of the head track. Another portion of the clip is inset slightly from the inner surface of the head track flanges. This inset portion includes grooves which accommodate the inwardly turned flanges on a standard stud. This allows the stud to slide up and down over the exterior of the clip between it and the flanges of the head track. The system is designed so that the length of the stud extends into or nestles within the downwardly turned flanges of the head track. If the clip were to be extended beyond these downwardly depending flanges, it would interfere with the attachment of drywall to the stud, since portions of the clip directly underlie the inwardly edges of the stud. There also is no provision in this patent for allowing sliding movement of drywall portions relative to one another; so that drywall necessarily would need to be spaced a sufficient distance below the downwardly turned edges of the head track to accommodate the expected vertical movement in the finished installation. This in turn allows sound to travel over the top of the drywall portions of the walls, from one room to another.
A different approach to the problem is disclosed in the DeFrancesco U.S. Pat. No. 5,685,121. As with the Gilmour patent mentioned above, the system of DeFrancesco also does not provide any provision for drywall overlap; so that sound can travel over the top of a wall built with this system. In DeFrancesco, a clip is designed for a slip fit within the open end of a stud. The clip includes an outwardly flared portion at the top, which then is secured to the flanges of the head track. The clip is designed to extend a substantial distance downwardly into the open end of the stud; and it includes elongated slots in its sides. The slots are designed to accommodate fasteners for drywall, which then may be passed through the studs and into the slots to permit the slip fit movement. The system, however, does not allow for drywall butt joints. Such joints will result in fasteners located on opposite sides of the slots; and if such a butt joint were to be secured in the area of the clip, the fasteners would secure the clip and the stud together in a non-movable relationship. This would defeat the purpose of the whole system. In addition, the system of DeFrancesco, as well as the system of Gilmour, preclude the running of any conduit through the wide or inside portion of the studs, since the clips of both of these patents completely overlie this portion. Consequently, no conduit could be run through the stud/clip assembly without securing the parts together. If conduit is run immediately below the clip, the relative vertical movement which is desired would be prevented, or severing of the conduit (and the wires within it) could result. As a consequence, the structures of both Gilmour and DeFrancesco clearly limit the location of any conduit running through the interior of the wall to a position substantially removed from the clip assembly itself.
The Becker U.S. Pat. Nos. 5,471,805 and 5,755,066 disclose a head track configuration with stepped surfaces to allow drywall overlap. This permits drywall attached to the header to slide over drywall attached to the studs which extend up into the header. This feature in the Becker patents provides a fire barrier connection, as well as a sound barrier. The disclosure of the Becker patents, however, does not show any guide whatsoever to hold the studs against tipping or shifting within the header. The studs are not held vertically within the header; and the only thing which holds the studs in their correct orientation is the connection of the drywall itself. The studs do not extend all the way to abut the header; so that limited vertical movement between the header and the top of the studs is permitted with this structure, allowing the overlapping drywall to slidably provide the necessary fire barrier. In the event of an earthquake, however, the studs are not held against lateral movement (particularly longitudinally of the header); so that the wall structure is subject to substantial damage in the event of an earthquake.
The Mieyal U.S. Pat. No. 4,397,127 discloses a stud extension with a slip fit onto the stud to then allow the stud to be interconnected with a suitable header. This extension allows a slip fit of the stud on the extension; but the extension itself has snap tabs on it to connect into the header. This requires additional manufacturing steps.
The Greenwood U.S. Pat. No. 5,146,723 is directed to an interior wall mounting device for providing a cosmetic interconnection between drywall sections which are vertically mounted on studs in the wall, and, in some cases, interconnections between drywall interfaces at both the ceiling and in corners of the room. The mounting devices are in the form of elongated parts which provide surfaces acting as crown molding, corner molding, or the like, in the finished construction. The structure disclosed in this patent, however, is not directed to slip fit interconnections between a head track and vertical studs to allow relative movements between the two.
Accordingly, it is an object of this invention to provide an improved stud and clip assembly which overcomes the disadvantages of the prior art, which effectively provides alignment for the studs while allowing relative movement between head track and the studs, and which allows a non-interfering location for the various components to allow standard connection of drywall and conduit passage at any location on the stud.